1. Field of the Invention
The present invention relates to a body cavity interior observing apparatus, in particular, a body cavity interior observing apparatus for performing various treatments while an image of a body cavity interior of an object to be examined is displayed on a monitor.
2. Description of the Related Art
A laparoscopic apparatus is a body cavity interior observing apparatus, and after a trocar (penetrating instrument) is stabbed into the body cavity interior through a abdominal part surface of a patient, and a laparoscope inserting section is inserted into the body cavity interior with help of the trocar as a guide, the laparoscopic apparatus is used to perform various treatments such as a treatment of adhesion while displaying a presence or absence of adhesion of a body cavity interior, or an image of a body part of an object to be examined such as ovarian tumor and hysteromyoma on a monitor. The laparoscope is held by a movable holder which is mounted to a fixing section to be maintained in a fixed state in clinical practice (for example, see Japanese Patent Application Laid-Open No. H8-164148).
In clinical practices that use such a laparoscopic apparatus, in order to observe a body part of an object to be examined which is actually treated at the central part of a monitor screen, a position of a distal end portion of a treating instrument which is located inside of a body cavity is detected so that the distal end portion of the treating instrument can be tracked to constantly align the position of the distal end portion to the central part of an image displayed on a monitor. The tracking mechanism described in the Japanese Patent Application Laid-Open No. H8-164148 includes a magnetic three-dimensional position sensor which is mounted to a part of laparoscope located outside of a patient's body. The magnetic three-dimensional position sensor includes a magnet source which is mounted to the laparoscope, and a magnetic sensor which is mounted to a treating instrument, and is configured to obtain position information of the distal end portion of the treating instrument located inside of a body cavity by calculating the position of the distal end portion of the treating instrument, which is used for a treatment and is located in the body, from a mount position of the magnetic sensor outside of the body by using a rotation/translation coordinate transformation.
In a laparoscopic apparatus having the tracking mechanism, as the treating instrument moves, an observation image which is displayed on a monitor screen continuously moves, resulting in that, every time the treating instrument is moved for operations of various treatments and examinations of an affected area, the monitor screen wobbles, which may be troublesome for a practitioner in observing or treating of an affected area.
Japanese Patent Application Laid-Open No. H9-266882 discloses a laparoscopic apparatus which solves such a trouble. In the laparoscopic apparatus, a monitor screen is divided into a central non-tracked region and an outer tracked region which surrounds the non-tracked region, so that when a treating instrument moves into the tracked region out of the non-tracked region, a tracking function is turned on to move an image of the treating instrument to the central part of the monitor screen, while when the treating instrument is located in the non-tracked region, the tracking function is turned off to prevent the wobble of the observation image.